In connection with a fire decision made on the basis of a plurality of sensor levels that vary with time and are detected time-serially as detection information representative of physical quantities involved in a fire phenomenon, there can be conceived a so-called discriminative pattern identification method according to which a table containing patterns based on a plurality of time-serial sensor levels together with fire information for each of the patterns is prepared and stored in a ROM or the like, wherein the pattern information in the table is compared with time-serial sensor levels actually detected, for thereby allowing the fire decision to be made.
Further, it is also conceivable to define a function having as variables the values of a plurality of time-serial sensor levels, wherein the fire decision is made on the basis of input/output relations with the aid of the function.
In any case, the decision as to whether or not a fire is occuring is based on the detected sensor levels. In this conjunction, it is extremely desirable if the fire monitoring operation can be effectuated with highly improved accuracy by virtue of the capability to finely and thoroughly monitor fire phenomena inclusive of smoldering fires and flaming fires while making available the information concerning the possibility of a fire, i.e. fire probability and the level of danger as well as the capability of eliminating the possibility of false alarm generation due to noise or other causes.
Accordingly, a first object of the present invention is to provide a fire alarm system for making a decision as to the occurrence of a fire on the basis of a plurality of sensor levels detected time-serially, a system which is not only capable of making a decision as to the occurrence of a fire but also capable of finely and thoroughly monitoring the fire probability and the level of danger as well as fire phenomena inclusive of smoldering fires and flaming fires with regard to such situations or states which may lead to a fire while eliminating the possibility of erroneous or false alarm generation from the influence of noise or the like.
In case fire information corresponding to a plurality of time-serial sensor levels should be defined in a table stored in a ROM or the like as described above in an effort to accomplish the above object, an increase in the number of input points or data would involve a more explosive increase in the number of combinations of such inputs, requiring prodigious labor and a large capacity ROM table for describing all the combinations, which would be practically impossible. Further, description of the input/output relations in terms of the functions as mentioned above is also practically impossible because of the limitation encountered in expressing such complex relations, not to say of the elimination of the possibility of erroneous or false alarm generation due to the influence of noise by the method relying on a table or function.
Accordingly, a second object of the present invention is to provide a fire alarm system having a signal processing structure suited for achieving the first object mentioned above.